.disable | .enable materialized-view

Disables or enables the materialization process for a materialized view.

Permissions

You must have at least Materialized View Admin to run these commands.

Syntax

.enable | disable materialized-view MaterializedViewName

Learn more about syntax conventions.

Parameters

Name	Type	Required	Description
MaterializedViewName	string	✔️	Name of the materialized view.

Returns

If the materialized view is already in the state in which the command is trying to set it to, the command fails with an error indicating that is the case.

Otherwise, it returns the details about the materialized view whose IsEnabled property has been changed.

Output schema:

Name	Type	Description
Name	string	Name of the materialized view.
SourceTable	string	Name of source table on which the view is defined.
Query	string	Query definition of the materialized view.
MaterializedTo	datetime	Maximum materialized ingestion_time() timestamp in source table. For more information, see how materialized views work.
LastRun	datetime	Last time materialization was run.
LastRunResult	string	Result of last run. Returns Completed for successful runs, otherwise Failed.
IsHealthy	bool	true when view is considered healthy, false otherwise. View is considered healthy if it was successfully materialized up to the last hour (MaterializedTo is greater than ago(1h)).
IsEnabled	bool	true when view is enabled (see Disable or enable materialized view).
Folder	string	Folder under which the materialized view is created.
DocString	string	Description assigned to the materialized view.
AutoUpdateSchema	bool	Whether the view is enabled for auto updates.
EffectiveDateTime	datetime	Effective date time of the view, determined during creation time (see .create materialized-view).
Lookback	timespan	Time span limiting the period of time in which duplicates are expected.

Examples

Enable a materialized view

The following command enables materialized view ViewName:

.enable materialized-view ViewName

Output

Name	SourceTable	Query	MaterializedTo	LastRun	LastRunResult	IsHealthy	IsEnabled	Folder	DocString	AutoUpdateSchema	EffectiveDateTime	Lookback
ViewName	TableName	TableName | summarize arg_max(Column3, *) by Column1	2023-02-26T16:40:03.3345704Z	2023-02-26T16:44:15.9033667Z	Completed	true	true			false	2023-02-23T14:01:42.5172342Z

Disable a materialized view

The following command disables materialized view ViewName:

.disable materialized-view ViewName

Output

Name	SourceTable	Query	MaterializedTo	LastRun	LastRunResult	IsHealthy	IsEnabled	Folder	DocString	AutoUpdateSchema	EffectiveDateTime	Lookback
ViewName	TableName	TableName | summarize arg_max(Column3, *) by Column1	2023-02-26T16:40:03.3345704Z	2023-02-26T16:44:15.9033667Z	Completed	true	false			false	2023-02-23T14:01:42.5172342Z

Remarks

Disabling materialized views

A materialized view can be disabled in any of the following ways:

• Automatic disable by the system: Materialized view is automatically disabled if materialization fails with a permanent error. This process can occur in the following instances:
  • Schema changes that are inconsistent with the view definition.
  • Changes to source table that result in the materialized view query being semantically invalid.
• Explicitly disable the materialized view: If the materialized view is negatively impacting the cluster's health (for example, consuming too much CPU), disable the view using the .disable materialized-view command.

Materialized views and Row Level Security

If a materialized view is disabled, and while the view is disabled someone defines a row level security policy on the source table of the view, but the materialized view doesn't have a row level security policy defined, then enabling the view fails for security reasons. To mitigate this error, you can:

• Define the row level security policy over the materialized view.
• Choose to ignore the error by adding allowMaterializedViewsWithoutRowLevelSecurity property to the enable policy command. For example:

    .enable materialized-view MV with (allowMaterializedViewsWithoutRowLevelSecurity=true)

Performance implications of enabling/disabling materialized views

• When a materialized view is disabled, materializing will be paused and won't consume resources from the cluster. Querying the materialized view is possible even when disabled, but performance can be poor. Performance on a disabled materialized view depends on the number of records that were ingested to the source table since it was disabled.
• You can enable a materialized view that has previously been disabled. When re-enabled, the materialized view will continue materializing from the point it left off, and no records will be skipped. If the view was disabled for a long time, it may take a long time to catch up.
• Disabling a view is only recommended if you suspect that the view is impacting your cluster's health.